Patterned helical metallic ribbon for continuous edge winding applications

ABSTRACT

Metallic ribbon having cutout patterns therein is provided in continuous helical form. The cutout patterns may be situated to intersect either or both of the ribbon edges or may be situated entirely within the ribbon. The helical ribbon with the cutout patterns may additionally have a nesting, or self-stacking, feature.

The United States Government has rights in this invention as claimedpursuant to contract number DE-AC01-78ET29313 between the United StatesDepartment of Energy and the General Electric Company (41 CFR §9-9.109).

This application is a division of application Ser. No. 972,239 filedDec. 22, 1978, which is now U.S. Pat. No. 4,341,845.

The invention herein is related to the invention disclosed and claimedin copending application Ser. No. 249,033, filed Mar. 30, 1981, in thenames of the same inventive entity as the instant application, assignedto the same assignee as the instant application, and entitled "Method ofMaking Patterned Helical Metallic Ribbon for Continuous Edge WindingApplications" which is now U.S. Pat. No. 4,343,347; said Ser. No.249,033 application is a divisional application of Ser. No. 972,240,filed Dec. 22, 1978, which, in turn, is now U.S. Pat. No. 4,281,706.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to patterned metallic ribbons in helical form forcontinuous edge winding applications.

2. Description of the Prior Art

The fabrication of glassy alloy magnetic ribbon for use in electricmotor applications is commonly believed to involve conventional punchingoperations performed on sheets or strips of the ribbon. However, a lowfilling or packing factor will result from conventional or prior artlaminations of known glassy alloys because of the greater number ofpunchings required when compared with the number of punchings requiredwhen using prior art materials for laminations. This is because of theinherent limit on thickness in melt-quenched glassy alloy specimens. Theoverall effect is to increase the size and cost of the finished electricmotor, thereby negating the savings offered by use of the glassy alloymaterial. A prior art method of making glassy alloy ribbon is to extrudethe alloy in molten form through an appropriate orifice in a crucibleand to subsequently impinge the melt jet onto the circumferentialsurface of a rapidly rotating substrate wheel. The melt jet axis istypically made to lie parallel to the plane of the substrate wheel. Theribbon so formed has the shape of conventional tape or ribbon and can bewound upon a spool.

It would be desirable to manufacture a motor stator comprising twoconcentric pieces of material. A center piece would be prefabricatedwith teeth and windings. The outer piece would be prefabricated or builtin situ from an edge-wound strip in the form of a large helix,

Therefore, it is an object of this invention to provide patternedmetallic ribbon in a continuous helical form.

Another object of this invention is to provide a new and improvedpatterned edge-wound glassy alloy magnetic ribbon in a helical form.

A further object of this invention is to provide patterned edge-woundmetallic or glassy alloy magnetic ribbon in a nested helical form.

A still further object of this invention is to provide edge-woundmetallic or glassy alloy magnetic ribbon with prefabricated cutoutstherein for making, as an example, a motor stator.

Other objects of this invention will, in part, be obvious and will, inpart, appear hereinafter.

BRIEF DESCRIPTION OF THE INVENTION

In accordance with the teachings of this invention, there is provided acontinuous length of patterned edge-wound metallic ribbon having ahelical shape, a substantially uniform cross-section and an axis normalto the plane of the helix. The ribbon has an inner peripheral edge andan outer peripheral edge as well as a pair of substantially parallel,opposed major surfaces. The composition of the ribbon may be that of aglassy alloy system which may be successfully produced by rapidquenching from the melt. Typical examples of such systems are Fe-B,Fe-B-C, Fe-B-Si, Fe-Ni-B, Cu-Zr and the like.

The ribbon is formed in situ with predetermined geometrically shapedcutouts in the inner and/or outer edges and/or between the edges of theribbon. Additionally, the ribbon may be formed in such a manner wherebythe helical coil is nested in such a fashion that the helix axis is notparallel to the local normal to the ribbon surface. This cast ribbon issuitable, for example, for use in making appropriately designedelectrical devices.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view illustrating fabrication of edge-woundmetallic ribbon in a helical form.

FIG. 1a is a top planar view of the schematic of FIG. 1 showing theazimuthal orientation of the melt flow axis in relation of the area ofstream impingement on the moving substrate surface 22.

FIG. 2 is a partial cross-section schematic view of fabricating a nestededge-wound metallic ribbon in a helical form.

FIG. 3 is a partial cross-section side elevation view of a nestededge-wound metallic ribbon.

FIG. 4 is a partial cross-section schematic view of fabricating a nestededge-wound metallic ribbon in a helical form.

FIG. 5 is a partial cross-section side elevation view of a nestededge-wound metallic ribbon.

FIGS. 6, 7 and 8 are schematic views of fabricating an edge-woundmetallic ribbon with a continuous pattern of predetermined periodicgeometry in either one or both of the inner or the outer peripheraledges of the ribbon.

FIG. 9 is a schematic of a portion of ribbon illustrating a continuousgeometric pattern within the ribbon.

DESCRIPTION OF THE INVENTION

Referring now to FIG. 1, there is shown a method of making edge-woundmetallic ribbon 10. Within the limits of the present invention, a ribbonis a thin body whose transverse dimensions are very much smaller thanits length. The ribbon 10 is formed by impinging a melt stream or jet 12onto a moving substrate surface 13 of a substrate wheel 14, rotatingabout axis 20, by extrusion of the molten alloy through an appropriateorifice 16 of a crucible 18. The axis 15 of the melt stream or jet 12 ismade to lie in a plane 26 defined by the tangent to the rotation of thesubstrate wheel 14 at the point of melt stream or jet axis 15intersection 24 and by the normal to the local substrate surface 22 atthe same point 24. Upon impingement of the melt stream or jet 12 ontothe portion 22 of the moving substrate surface 13 of the wheel 14, themelt is chilled into the shape of the ribbon 10 which assumes an inplanecurvature defined by the motion of the wheel at the area of impingement24. The width of the ribbon formed at the melt stream or jet impingementarea 24 determines the radius of the inner and outer peripheral edge Riand Ro, respectively, of the edge-wound helical metallic ribbon 10.

The melt stream or jet axis 15 in the plane described may intersect theportion 22 of the moving substrate surface 13 at an angle α typicallybetween 30° and 90°, with the range 40°≦α≦70° preferred for optimizedribbon geometric uniformity. The structure of the resulting metallicribbon may be crystalline or glassy. Glassy metallic ribbon may be madefrom a glassy alloy system obtainable by rapid quenching from the melt.Typical examples of glossy alloy systems are Fe-B, Fe-B-C, Fe-B-Si,Fe-Ni-B, Cu-Zr and the like.

It has been empirically found that the edge-wound ribbon most readilyforms within certain limits of melt stream or jet velocity and substratesurface velocity. The preferred melt stream or jet velocity should rangefrom about 1 m/s to about 10 m/s. The substrate surface speed preferablyranges from about 12 m/s to about 50 m/s. Precautions must be taken toassure intimate contact between the substrate surface and the coolingribbon for a sufficient length of time in order to form a suitablehelix. One particular method is to roughen the surface of the substratewheel and thereby prolong ribbon dwell time on the surface of the wheel.Another method is to employ a gas or mechanical type of "hold-down"device which is well known to those skilled in the art.

The ribbon as formed has a substantially uniform cross-section whencompared with helical products fabricated by mechanical means ofdeformation such, for example, as by cambered rolling. The latterproducts typically have a tapered cross-section wherein the thickness ofthe ribbon is uniformly reduced towards the outer peripheral edge acrossthe width of the ribbon.

With reference to FIGS. 1 and 1a, the possible orientations of thecrucible axis with respect to the moving substrate surface may bedefined by an inverted cone with apex at the point of stream axisimpingement. This cone is defined by the inclination and azimuthalangles α and γ, respectively. Using the projection as an arbitraryreference marker, the azimuthal angle may have values of 0≦|γ|≦180°."Backstreaming" occurs when |γ|>90°, thereby resulting in ribbon 10formed in the direction of substrate motion and in droplets or acontinuous stream formed against the general direction of substratemotion, sometimes resulting in a continuous fiber.

When the melt stream or jet 12 is made to impinge onto a beveled surface50, that is, a portion of the substrate surface 13 which is modified byshaping it to be integral with and inclined to the remaining portion ofthe surface 13 of the rotating substrate wheel 14, an edge-wound helicalmetallic ribbon results and has a nesting angle somewhat less than thatof the bevel inclination on the rotating substrate wheel 14. The surface50 intersects the substrate surface 13 and forms the included obtuseangle β therewith. For example, with reference to FIGS. 2 and 3, themelt jet 12 from crucible 18 is made to impinge upon the beveled surface50 of the wheel 14 in plane 26 previously described.

The melt stream or jet 12, which is directed onto the moving substratesurface 50, has an axis 15 lying in plane 26 and inclined at 30°≦α≦90°with the surface 50. The plane 26 is defined by the tangent to therotation of the substrate wheel 14 at the point of melt stream or jetaxis 15 intersection 24 and by the normal to the local substrate surface50 at the same point 24. The range 40°≦α≦90° is preferred for optimizedribbon geometry.

A nested glassy alloy ribbon 54 which is produced has parallel surfaces56 and 58 inclined away from the central axis 20 of the helical coil 20.

Alternately, as shown in FIGS. 4 and 5, the melt stream or jet 12 fromcrucible 18 is made to impinge on a beveled surface 60 formed in theouter portion 62 of the substrate surface 13 of the wheel 14. Thesurface 60 intersects an extension of the surface 13 of the wheel 14 andforms an included acute angle β therewith. The melt stream or jet 12,which is directed onto the moving substrate surface 60, has an axis 15lying in plane 26 and inclined at 30°≦α≦90° with the surface 60. Theplane 26 is defined by the tangent to the rotation of the substratewheel 14 at the point of melt stream or jet axis 15 intersection 24 andby the normal to the local substrate surface 60 at the same point 24.The range 40°≦α≦70° is preferred for optimized ribbon geometry. Thenested metallic ribbon 64 which is produced has substantially parallelsurfaces 66 and 68 which are inclined toward the central axis 20 of thehelical coil.

Referring to FIG. 6, the portion 22 of the moving substrate surface 13on the rotating substrate wheel 14 may be modified in order to form ametallic ribbon 70 with predetermined cutout regions therein. Thesubstrate surface portion 22 is modified by suitable means to containbarrier lines. For example, such lines may be introduced by scribingwith a sharp-edged tool or by a silk screening ink application toproduce a plurality of lines 72 which define the geometric configurationof the cutout to be made in the inner peripheral portion of the ribbon70. The lines 72 provide a differential cooling rate between the moltenmetal cast on the lines 72 and the metal cast on the substrate surfaceportion 22. The lines 72 made either by the removal of material from thesubstrate surface portion 22 or by the application of ink provide abarrier which prevents the cast metal from cooling rapidly in thevicinity thereof. Therefore, the alloy cast as the result of the contactof the melt and the moving substrate surface portion 22 produces themetallic ribbon. Centrifugal force causes the ribbon 70 to be cast fromthe wheel after an adequate dwell time required to define the helicalshape and causes the portion of the ribbon 70 enclosed by scribe marksto break or flake away and produce individual amorphous flakes orplatelets 74. The ribbon 70 is suitable for many types ofelectromagnetic devices such as, for example, the rotor and statorportions of an electric motor, and applications requiring a pre-definedair gap such as in a ballast or in a linear reactor.

With reference to FIG. 7, there is shown another alternate embodiment ofthe ribbon 10. In this instance, lines 80 are made on the substratesurface portion 22 of the wheel 14 to form metallic ribbon 82 suitablefor use in making the rotor portion of an electric motor. Again,metallic flakes 84 are a by-product. The cutouts are made in the outerperipheral portion of the ribbon 82.

The glassy alloy ribbons 70 and 82 may be employed in AC motors asstated heretofore. The ribbon 70 may be utilized in an AC motor statorfor a squirrel cage induction or synchronous motor. The ribbon 82 issuitable for the direct casting of one or more components of an AC motorfor squirrel cage induction, synchronous with or without amortisseurwinding, or hysteresis motors as well as DC or universal motor parts.

Alternately, the barrier imposed by the scribe lines 72 and 80 may beobtained by employing a low thermal conducting, a non-thermalconducting, or a non-wetting medium to delineate the pattern of theflakes 74 and 84.

The flakes or platelets 74 and 84 may be employed in making compositesor encapsulated shaped articles made from the flakes.

Referring now to FIG. 8, there is shown a ribbon 90 which embodiescutouts in both the inner and outer peripheral edges of ribbon 90. Theribbon 90 is manufactured in a process which embodies a process verysimilar to that required for producing ribbons 70 and 82. Metallicflakes are a by-product of the process.

The following Examples are illustrative of the teachings of thisinvention:

EXAMPLE I

The substrate was provided by the face of a 7.5 cm diameter OFHC copperwheel as shown in FIG. 1 finished with 400 grit emery paper and rotatingat 8500 rpm. Angles α and γ were set at 50° and 0°, respectively. Theangle β was 180°. The Fe₄₀ Ni₄₀ B₂₀ molten alloy jet was at 1200° C. andwas formed by extrusion under 60 kPa Ar driving pressure through a 500μm hole in a clear fused quartz crucible. The point of melt jetimpingement was at a radius of 3 cm from the axis of the rotating wheel.The resultant product was a glassy alloy helix with average diameter 6cm, ribbon width 0.9 mm, and ribbon thickness 38 μm, as measured by amicrometer.

EXAMPLE II

The substrate was provided by the face of a 7.5 cm diameter OFHC copperwheel as shown in FIG. 1 finished with 400 grit emery paper and rotatingat a speed resulting in 35 m/s substrate surface speed at point ofimpingement. Angles α and γ were set at 70° and 0°, respectively. Theangle β was 150°. The Fe₄₀ Ni₄₀ B₂₀ jet was formed by pressurizationwith 60 kPa Ar and extrusion of the melt through a 500 μm round orificeat 1200° C. The resulting helical glassy alloy ribbon sample has anaverage diameter equal to that of the wheel at the point of melt jetimpingement. The nesting angle of the helix was some 10°-15° less thanβ.

Although the invention has been described relative to the employment ofa free jet stream impinging upon the moving substrate surface to form adynamic melt puddle from which ribbon is drawn, the apparatus of M. C.Narasimhan, appropriately modified, may be employed as well. Theapparatus and process of using it is taught in Belgian Pat. No. 859,694issued Jan. 2, 1978. In the apparatus of M. C. Narasimham, the moltenalloy jet stream is kept confined to within a full breadth of the slitused in casting.

The invention has been described with the possible embodiment of acontinuous pattern of geometric cut-outs in either or both of theperipheral portions of the ribbon. However, a continuous pattern of aspecific geometrical configuration may also be provided within theribbon itself in order to meet motor performance standards. Withreference to FIG. 9, there is shown a portion 100 of a ribbon 104 havingwalls 102 defining a cut-out in the ribbon which is part of a continuouspattern. The ribbon 104 is manufactured in the same manner as theprevious ribbons and employing the same barrier line technique to obtainthe continuous pattern. The cut-outs may be of any planar geometricalconfiguration and are determined by the required motor performance forwhich the ribbon is employed.

We claim as our invention:
 1. A continuous length of cast edge-woundpatterned metallic ribbon having a permanent cast-in helical shape witha substantially glassy microstructure, a pair of substantially parallelopposed major surfaces, an inner peripheral edge, an outer peripheraledge, and a predetermined pattern of cut-outs.
 2. The cast edge-woundribbon of claim 1 wherein said helical shaped ribbon also has apermanently cast-in nesting feature such that the normal to the planesof said opposed major surfaces is inclined away from longitudinal axis20 of the coil when the direction of said normal is taken from surface56 to surface
 58. 3. The cast edge-wound ribbon of claim 1 wherein saidhelical shaped ribbon also has a permanently cast-in nesting featuresuch that the normal to the planes of said opposed major surfaces isinclined toward longitudinal axis 20 of the coil when the direction ofsaid normal is taken from surface 66 to surface
 68. 4. The castedge-wound ribbon of claim 1 wherein said cut-outs in said patternintersect at least one of said inner and outer peripheral edges of saidribbon.
 5. The cast edge-wound ribbon of claim 1 whereinsaid metallicribbon has a glassy structure.
 6. The cast edge-wound ribbon of claim 1whereinsaid metallic ribbon is made of a glassy alloy selected from oneof the glassy alloy systems in the group consisting of Fe-B, Fe-B-C,Fe-B-Si, Fe-Ni-B and Cu-Zr.
 7. The cast edge-wound ribbon of claim 1wherein said cutouts in said pattern are located interior to both saidinner and outer peripheral edges of said ribbon.
 8. The cast edge-woundribbon of claim 1 whereinsaid cut-outs in said pattern intersect bothsaid inner peripheral edge and said outer peripheral edge of saidribbon.